I hate to admit how effective these are. I have birds and it scared the living bird dust outta me when I changed the filters. Good grief. How did I live without these before? Yes, the filters are pricey , for me, because I have to replace them but its because they are working!
I am ordering more. These are fabulous. Taking one over to my moms house right now for her to have.
If you think its clean, its not, unless you have one of these. Try it, you ttoo might be scarily surprised at how much gunk that these babies pick up that you arent aware of.
ps they are a bit noisy, but to us that white noise is very calming